U.S. patent number 7,882,752 [Application Number 12/086,089] was granted by the patent office on 2011-02-08 for sensor-equipped bearing for wheel.
This patent grant is currently assigned to NTN Corporation. Invention is credited to Tomomi Ishikawa, Kentarou Nishikawa, Takayoshi Ozaki.
United States Patent |
7,882,752 |
Ozaki , et al. |
February 8, 2011 |
**Please see images for:
( Certificate of Correction ) ** |
Sensor-equipped bearing for wheel
Abstract
The wheel support bearing assembly is for rotatably supporting a
vehicle wheel relative to an automotive vehicle body, which
includes an outer member having an inner periphery formed with a
plurality of rows of raceway surfaces, an inner member having
raceway surfaces formed therein in face-to-face relation with the
raceway surfaces in the outer member, and a plurality of rows of
rolling elements interposed between those raceway surfaces,
respectively; a sensor unit including a sensor mounting member and
a strain sensor fitted to the sensor mounting member, the sensor
unit being fitted to a stationary member, which is one of the outer
member and the inner member; and wherein the sensor mounting member
includes at least two contact fixing portion relative to the
stationary member and the strain sensor is arranged at at least one
location between the contact fixing portions.
Inventors: |
Ozaki; Takayoshi (Iwata,
JP), Ishikawa; Tomomi (Iwata, JP),
Nishikawa; Kentarou (Iwata, JP) |
Assignee: |
NTN Corporation (Osaka,
JP)
|
Family
ID: |
38122739 |
Appl.
No.: |
12/086,089 |
Filed: |
December 1, 2006 |
PCT
Filed: |
December 01, 2006 |
PCT No.: |
PCT/JP2006/324070 |
371(c)(1),(2),(4) Date: |
June 05, 2008 |
PCT
Pub. No.: |
WO2007/066593 |
PCT
Pub. Date: |
June 14, 2007 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20090038414 A1 |
Feb 12, 2009 |
|
Foreign Application Priority Data
|
|
|
|
|
Dec 8, 2005 [JP] |
|
|
2005-354245 |
Dec 13, 2005 [JP] |
|
|
2005-358588 |
Dec 13, 2005 [JP] |
|
|
2005-358589 |
|
Current U.S.
Class: |
73/862.322 |
Current CPC
Class: |
B60B
27/0068 (20130101); F16C 19/522 (20130101); B60B
27/0005 (20130101); G01L 5/0023 (20130101); B60B
27/0094 (20130101); G01P 3/443 (20130101); F16C
33/58 (20130101); F16C 2326/02 (20130101); F16C
19/186 (20130101) |
Current International
Class: |
G01L
3/14 (20060101) |
Field of
Search: |
;73/862.322 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1455233 |
|
Nov 2003 |
|
CN |
|
2531492 |
|
Jan 1997 |
|
JP |
|
2002-340922 |
|
Nov 2002 |
|
JP |
|
2003-530565 |
|
Oct 2003 |
|
JP |
|
2003-336653 |
|
Nov 2003 |
|
JP |
|
2004-3601 |
|
Jan 2004 |
|
JP |
|
2004-155261 |
|
Jun 2004 |
|
JP |
|
2004-198247 |
|
Jul 2004 |
|
JP |
|
2004-360782 |
|
Dec 2004 |
|
JP |
|
2005-265175 |
|
Sep 2005 |
|
JP |
|
2006-003268 |
|
Jan 2006 |
|
JP |
|
2006-010477 |
|
Jan 2006 |
|
JP |
|
2006-077807 |
|
Mar 2006 |
|
JP |
|
2007-071280 |
|
Mar 2007 |
|
JP |
|
01/77634 |
|
Oct 2001 |
|
WO |
|
2004/018273 |
|
Mar 2004 |
|
WO |
|
Other References
International Preliminary Report on Patentability mailed on Nov.
27, 2008 and issued in corresponding International Patent
Application No. PCT/JP2006/324070. cited by other .
International Search Report mailed Jan. 9, 2007 in connection with
International Application No. PCT/JP2006/324070. cited by other
.
U.S. Appl. No. 11/991,480, filed Mar. 5, 2008, Ozaki et al. cited
by other .
U.S. Appl. No. 12/086,153, filed Jan. 6, 2008, Ozaki et al. cited
by other .
U.S. Appl. No. 12/224,846, filed Sep. 8, 2008, Ozaki et al. cited
by other .
Office Action dated May 7, 2010 in co-pending U.S. Appl. No.
12/224,846. cited by other .
U.S. Notice of Allowance mailed Aug. 25, 2010 and issued in related
U.S. Appl. No. 12/224,846. cited by other.
|
Primary Examiner: Caputo; Lisa M
Assistant Examiner: Davis; Octavia
Claims
What is claimed is:
1. A sensor equipped wheel support bearing assembly to rotatably
support a vehicle wheel relative to a vehicle body structure,
comprising: an outer member having an inner periphery formed with a
plurality of rows of raceway surfaces, an inner member having
raceway surfaces formed therein in face-to-face relation with the
raceway surfaces in the outer member, and a plurality of rows of
rolling elements interposed between those raceway surfaces,
respectively; and a sensor unit comprising a separate sensor
mounting member and a strain sensor or a displacement sensor fitted
to the sensor mounting member, or a mounting member made of a
magnetostrictive material and a detecting coil fitted to the
mounting member, the sensor unit being fitted to a stationary
member, which is one of the outer member and the inner member; and
wherein the sensor mounting member or the mounting member made of
the magnetostrictive material includes at least two contact fixing
portion relative to the stationary member and the strain sensor,
the displacement sensor or the detecting coil is arranged at least
one location between the contact fixing portions.
2. The sensor equipped wheel support bearing assembly as claimed in
claim 1, wherein the stationary member, which is one of the outer
member and the inner member, includes vehicle body fitting holes,
the neighboring two vehicle body fitting holes adjacent a road
surface or remote from the road surface are spaced a distance
corresponding to a phase difference of 80.degree. or more, and the
sensor unit comprising the sensor mounting member and the strain
sensor or displacement sensor is fitted between the neighboring two
vehicle body fitting holes, and wherein the sensor mounting member
has at least one recess between the neighboring contact fixing
portions and the strain sensor is arranged in this recess.
3. The sensor equipped wheel support bearing assembly as claimed in
claim 2, wherein the stationary member is the outer member.
4. The sensor equipped wheel support bearing assembly as claimed in
claim 1, wherein the sensor unit comprises the mounting member made
of the magnetostrictive material and the detecting coil, and the
mounting member has at least one recess between the neighboring
contact fixing portions and the detecting coil is arranged in this
recess.
5. The sensor equipped wheel support bearing assembly as claimed in
claim 4, wherein the stationary member is the outer member.
6. The sensor equipped wheel support bearing assembly as claimed in
claim 4, wherein a first one of the contact fixing portions of the
sensor mounting member is fitted at a location where it is deformed
in a radial direction more than that at any other location of the
stationary member by an external force acting on the stationary
member or a working force acting between a wheel tire and the road
surface.
7. The sensor equipped wheel support bearing assembly as claimed in
claim 6, wherein a second one of the contact fixing portion is
rendered to be a location where a direction of a radial strain
caused by the external force acting on the stationary member or the
working force acting between the wheel tire and the road surface is
different oppositely.
8. The sensor equipped wheel support bearing assembly as claimed in
claim 1, wherein the sensor unit comprises the sensor mounting
member and the displacement sensor, and the contact fixing portions
are fitted to respective locations, which is not deformed in the
radial direction, as compared with at any other location of the
stationary member, by the external force acting on the stationary
member or the working force acting between the wheel tire and the
road surface.
9. The sensor equipped wheel support bearing assembly as claimed in
claim 8, wherein the displacement sensor is fitted to a location,
which is deformed in the radial direction, as compared with at any
other location of the stationary member, by the external force
acting on the stationary member or the working force acting between
the wheel tire and the road surface.
10. The sensor equipped wheel support bearing assembly as claimed
in claim 8, wherein the stationary member is the outer member.
Description
CROSS REFERENCE TO RELATED PATENT APPLICATIONS
This application claims the benefit under 35 U.S.C. Section 371, of
PCT International Application No. PCT/JP2006/324070, filed Dec. 1,
2006, which claimed priority to Japanese Application No.
2005-354245 filed Dec. 8, 2005, Japanese Application No.
2005-358588 filed Dec. 13, 2005, and Japanese Application No.
2005-358589 filed Dec. 13, 2005 in Japan, the contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a sensor equipped wheel support
bearing assembly having incorporated therein a sensor for detecting
a load imposed on a bearing area of a vehicle wheel.
For safety travel of an automotive vehicle, the wheel support
bearing assembly equipped with a sensor for detecting the
rotational speed of one of automotive wheels has hitherto been well
known in the art. While the automobile traveling safety precaution
is hitherto generally taken by detecting the rotational speed of a
wheel of various parts, it is not sufficient with only the
rotational speed of the wheel and, therefore, it is required to
achieve a control for safety purpose with the use of other sensor
signals.
In view of this, it may be contemplated to achieve an attitude
control based on a load acting on each of wheels during travel of
an automotive vehicle. By way of example, a large load acts on the
outside wheels during the cornering, on the wheels on one side
during the run along left and right inclined road surfaces or on
the front wheels during the braking, and, thus, a varying load acts
on the vehicle wheels. Also, even in the case of the uneven live
load, the loads acting on those wheel tend to become uneven. For
this reason, if the loads acting on the wheels can be detected as
needed, suspension systems for the vehicle wheels can be controlled
beforehand based on results of detection of the loads, so that the
attitude control of the automotive vehicle during the traveling
thereof (for example, prevention of a rolling motion during the
cornering, prevention of the front wheel diving during the braking,
and prevention of the vehicle wheels diving brought about by an
uneven distribution of live loads) can be accomplished. However, no
space for installation of the load sensor for detecting the load
acting on the respective vehicle wheel is available and, therefore,
the attitude control through the detection of the load can hardly
be realized.
Also, in the event in the near future the steer-by-wire is
introduced and the system, in which the wheel axle and the steering
come not to be coupled mechanically with each other, is
increasingly used, information on the road surface comes to be
required to transmit to the steering wheel hold by a driver by
detecting a wheel axle direction load.
In order to meet those needs hitherto recognized, the wheel support
bearing assembly has come to be suggested, in which a strain gauge
is applied to an outer ring of the wheel support bearing assembly
so as to detect the strain. (See, for example, the Japanese
Laid-open International Application No. 2003-530565).
SUMMARY OF THE INVENTION
The outer ring of the wheel support bearing assembly is a bearing
component part, which has raceway surfaces and is required to have
a strength and which is manufactured through complicated process
steps including, for example, plastic forming, turning, heat
treatment and grinding. For this reason, where the strain gauge is
fitted to the outer ring such as disclosed in the above mentioned
published patent document, there are problems in that the
productivity is low and the cost at the time of mass-production is
high.
An object of the present invention is to provide a wheel support
bearing assembly, in which a load detecting sensor can be installed
neatly and snugly, the load imposed on the vehicle wheel can be
detected, and the cost at the time of mass-production is low.
The sensor equipped wheel support bearing assembly according to the
first aspect of the present invention is a wheel support bearing
assembly for rotatably supporting a vehicle wheel relative to a
vehicle body structure, which includes an outer member having an
inner periphery formed with a plurality of rows of raceway
surfaces, an inner member having raceway surfaces formed therein in
face-to-face relation with the raceway surfaces in the outer
member, and a plurality of rows of rolling elements interposed
between those raceway surfaces, respectively; a sensor unit
comprising a sensor mounting member and a strain sensor or a
displacement sensor fitted to the sensor mounting member, or a
mounting member made of a magnetostrictive material and a detecting
coil fitted to the mounting member, the sensor unit being fitted to
a stationary member, which is one of the outer member and the inner
member; and wherein the sensor mounting member or the mounting
member made of the magnetostrictive material includes at least two
contact fixing portion relative to the stationary member and the
strain sensor, the displacement sensor or the detecting coil is
arranged at at least one location between the contact fixing
portions. For example, when the outer member is the stationary
member and the inner member is the rotatable member, the sensor
unit is fitted to the outer member.
Where the sensor unit includes the strain sensor, the stationary
member is deformed through the rolling elements when the load acts
on the rotatable member as the automotive vehicle runs, and such
deformation results in a strain in the sensor unit. The strain
sensor provided in the sensor unit detects the strain of the sensor
unit. If the relation between the strain and the load is determined
beforehand by means of a series of experiments and/or simulations,
the load or the like on the vehicle wheel can be detected from the
output from the strain sensor.
Where the sensor unit includes the displacement sensor, the
stationary member displaces through the rolling elements when the
load acts on the rotatable member as the automotive vehicle runs,
and such displacement is detected by the displacement sensor of the
sensor unit. If the relation between the displacement and the load
is determined beforehand by means of a series of experiments and/or
simulations, the load or the like on the vehicle wheel can be
detected from the output from the displacement sensor.
Where the sensor unit includes the detecting coil, the stationary
member is deformed through the rolling elements when the load acts
on the rotatable member as the automotive vehicle runs, and such
deformation results in a strain in the mounting member of the
sensor unit. The detecting coil provided in the sensor unit detects
the inverse magnetostrictive effect of the mounting member. If the
relation between the strain (inverse magnetostrictive effect) and
the load is determined beforehand by means of a series of
experiments and/or simulations, the load or the like on the vehicle
wheel can be detected from the output from the detecting coil.
In other words, the external force acting on the wheel support
bearing assembly, or the working force acting between the wheel
tire and the road surface, or the amount of preload in the wheel
support bearing assembly can be estimated in reference to the
output from the strain sensor, the displacement sensor or the
detecting coil, respectively. Also, the load so detected or the
like can be utilized in vehicle control of the automotive
vehicle.
Since this sensor equipped wheel support bearing assembly is such
that the strain sensor or the displacement sensor is fitted to the
sensor mounting member that is fitted to the stationary member, or
the detecting coil is fitted to the mounting member made of the
magnetostrictive material and fitted to the stationary member, the
load sensor can be snugly and neatly mounted on the automotive
vehicle. Since the sensor mounting member or the mounting member
made of the magnetostrictive material is a handy component part
that can be fitted to the stationary member, the productivity can
be rendered to be excellent and the cost can be reduced if the
strain sensor or the displacement sensor or the detecting coil is
fitted thereto.
Also, since where the sensor unit includes the displacement sensor,
the sensor mounting member of the sensor unit has at least two
contact fixing portions relative to the stationary member and at
least one displacement sensor is arranged between the neighboring
contact fixing portions, the deformation in the radial direction
occurs at the location of the displacement in the sensor mounting
member as a result of deformation of the stationary member and this
displacement can be detected by the displacement sensor, making it
possible to detect the displacement of the stationary member with
high precision.
The sensor equipped wheel support bearing assembly according to the
second constriction of the present invention is the sensor equipped
wheel support bearing assembly according to the first aspect, in
which of vehicle body fitting holes possessed by the stationary
member, which is one of the outer member and the inner member, the
neighboring two vehicle body fitting holes adjacent a road surface
and/or remote from the road surface are spaced a distance
corresponding to a phase difference of 80.degree. or more, wherein
the sensor unit comprising the sensor mounting member and the
strain sensor is fitted between the neighboring two vehicle body
fitting holes, and wherein the sensor mounting member has at least
one recess between the neighboring contact fixing portions and the
strain sensor is arranged in this recess.
The phase difference is 80.degree. or more and the vehicle mounting
holes, in which the sensor unit is fitted therebetween, may be the
two neighboring vehicle mounting holes adjacent the road surface or
the two neighboring vehicle mounting holes remote from the road
surface. Also, the phase difference for the neighboring vehicle
mounting holes adjacent the road surface and remote from the road
surface may be 80.degree. or more.
In general, the wheel support bearing assembly has various
component parts of high rigidity in order to secure the performance
thereof. Since for this reason, the strain occurring in the
stationary member is small, difficulty is often encountered in
detecting the working force acting between the wheel tire and the
road surface with the sensor unit. In this respect, in the second
aspect now under discussion, since the phase difference .alpha.
between the neighboring two vehicle body fitting holes adjacent the
road surface and/remote from the road surface, out from the vehicle
body fitting holes formed in the stationary member, is so chosen as
to be 80.degree. or more and the sensor unit is fitted in position
between those two neighboring vehicle body fitting holes spaced a
distance corresponding to such phase difference of 80.degree. or
more, the strain of the sensor mounting member is so considerable
that even the slightest strain occurring in the stationary member
can be detected with the sensor unit.
Also, since the sensor mounting member of the sensor unit has the
at least two contact fixing portions relative to the stationary
member and at least one recess is formed at a location intermediate
between the neighboring contact fixing portions with the strain
sensor arranged in this recess, the location where the strain
sensor of the sensor mounting member is arranged, when the rigidity
thereof is lowered, accompanies a more considerable strain than
that in the stationary member and the strain in the stationary
member can be detected with high precision.
The sensor equipped wheel support bearing assembly according to the
third aspect is the sensor equipped wheel support bearing assembly
according to the second aspect, in which the stationary member is
the outer member.
The sensor equipped wheel support bearing assembly according to the
fourth aspect is the sensor equipped wheel support bearing assembly
according to the first aspect, in which the sensor unit comprises
the mounting member made of the magnetostrictive material and the
detecting coil, and wherein the mounting member has at least one
recess between the neighboring contact fixing portions and the
detecting coil is arranged in this recess.
The mounting member of the sensor unit includes at least two
contact fixing portions relative to the stationary member and at
least one recess at a location intermediate between the neighboring
contact fixing portions, with the detecting coil arranged in such
recess. Accordingly, the location where the detecting coil of the
sensor mounting member is arranged, as the rigidity thereof is
lowered, accompanies a more considerable strain than that in the
stationary member and the strain in the stationary member can be
detected with high precision.
The sensor equipped wheel support bearing assembly according to the
fifth aspect is the sensor equipped wheel support bearing assembly
according to the fourth aspect, in which the stationary member is
the outer member.
In the fourth aspect, a first one of the contact fixing portions of
the sensor mounting member is preferably fitted at a location where
it is deformed in a radial direction more than that at any other
location of the stationary member by an external force acting on
the stationary member or a working force acting between a wheel
tire and the road surface. This is rendered to be the sensor
equipped wheel support bearing assembly according to the sixth
aspect.
In the stationary member, the extent to which the deformation takes
place in the radial direction under the influence of the external
force and/or the working force varies from place to place in the
circumferential direction thereof. According to the result of
analysis, the deformation of the stationary member in the radial
direction under the influence of an axial force acting at the point
of contact between the wheel tire and the road surface is at
maximum at the zenith position, which is remote from the road
surface, and at the right below position opposite to the zenith
position, which is adjacent the road surface. If the first contact
fixing portion is fitted to a location of the stationary member,
where more considerable deformation in the radial direction occurs
than that at any other remaining location of the stationary member,
the mounting member will be such that the first contact fixing
portion undergoes a considerable deformation accompanied by the
considerable deformation of the stationary member with the second
contact fixing portion accompanying less deformation providing the
fulcrum. Because of this, a more considerable strain will occur at
the mounting portion of the mounting member, where the detecting
coil is mounted, and the strain of the stationary member can be
detected by the detecting coil with higher sensitivity.
In the sixth aspect, a second one of the contact fixing portion may
be rendered to be a location where a direction of a radial strain
caused by the external force acting on the stationary member or the
working force acting between the wheel tire and the road surface is
different oppositely. This is rendered to be the sensor equipped
wheel support bearing assembly according to the seventh aspect.
If the second contact fixing portion and the first contact fixing
portion are rendered to be different locations in positive or
negative sign as to the strain of the stationary member in the
radial direction, respective strains in those directions are summed
together and the deformation of the stationary member can be well
transmitted to the mounting member and, therefore, a further
increased strain can be detected to allow the strain of the
stationary member to be detected with high sensitivity.
The sensor equipped wheel support bearing assembly of the present
invention according to the eighth aspect is such that in the sensor
equipped wheel support bearing assembly according to the first
aspect, the sensor unit comprises the sensor mounting member and
the displacement sensor, and the contact fixing portions are fitted
to respective locations, which is not deformed in the radial
direction, as compared with at any other location of the stationary
member, by the external force acting on the stationary member or
the working force acting between the wheel tire and the road
surface. Also, in this aspect, the displacement sensor is
preferably fitted to a location, which is deformed in the radial
direction, as compared with at any other location of the stationary
member, by the external force acting on the stationary member or
the working force acting between the wheel tire and the road
surface. This is rendered to be the sensor equipped wheel support
bearing assembly according to the ninth aspect.
In the stationary member, the extent to which the deformation takes
place in the radial direction under the influence of the external
force and/or the working force varies from place to place in the
circumferential direction thereof. According to the result of
analysis, the deformation of the stationary member in the radial
direction under the influence of an axial force acting at the point
of contact between the wheel tire and the road surface is at
maximum at the zenith position, which is remote from the road
surface, and at the right below position opposite to the zenith
position, which is adjacent the road surface. If the contact fixing
portion of the sensor mounting member is fitted to a location of
the stationary member, where no deformation in the radial direction
occurs as compared with any other remaining location of the
stationary member and the displacement sensor is fitted to a
location, where it deforms in the radial direction as compared with
that at any other remaining location of the stationary member, the
mounting portion of the sensor mounting member, where the
displacement sensor is mounted, will deform considerably in the
radial direction accompanying the deformation of the stationary
member and the displacement of the stationary member can be
detected by the displacement sensor with further high
sensitivity.
The sensor equipped wheel support bearing assembly according to the
tenth aspect is the sensor equipped wheel support bearing assembly
according to the eighth aspect, in which the stationary member is
the outer member.
BRIEF DESCRIPTION OF THE DRAWINGS
In any event, the present invention will become more clearly
understood from the following description of preferred embodiments
thereof, when taken in conjunction with the accompanying drawings.
However, the embodiments and the drawings are given only for the
purpose of illustration and explanation, and are not to be taken as
limiting the scope of the present invention in any way whatsoever,
which scope is to be determined by the appended claims. In the
accompanying drawings, like reference numerals are used to denote
like parts throughout the several views, and:
FIG. 1 is a longitudinal sectional view of a sensor equipped wheel
support bearing assembly according to a first preferred embodiment
of the present invention;
FIG. 2 is a front elevational view of an outer member employed in
the wheel support bearing assembly, as viewed from the outboard
side;
FIG. 3A is a side view of a sensor unit employed in the wheel
support bearing assembly;
FIG. 3B is a rear view of the sensor unit shown in FIG. 3A;
FIG. 4 is a diagram showing a longitudinal sectional view of the
wheel support bearing assembly together with a circuit block
diagram of a conceptual construction of a detecting system employed
therein;
FIG. 5 is a front elevational view showing another arrangement of
the sensor unit on the outer member, as viewed from the outboard
side;
FIG. 6 is a front elevational view showing a different arrangement
of the sensor unit on the outer member, as viewed from the outboard
side;
FIG. 7 is a longitudinal sectional view of the sensor equipped
wheel support bearing assembly according to a second preferred
embodiment of the present invention;
FIG. 8 is a front elevational view showing the outer member
employed in the wheel support bearing assembly as viewed from the
outboard side;
FIG. 9 is a longitudinal sectional view of the sensor equipped
wheel support bearing assembly according to a third preferred
embodiment of the present invention;
FIG. 10 is a front elevational view of the outer member employed in
the wheel support bearing assembly, as viewed from the outboard
side;
FIG. 11A is a side view of the sensor unit employed in the wheel
support bearing assembly;
FIG. 11B is a rear view of the sensor unit;
FIG. 12 is an explanatory diagram showing a sectional view of the
wheel support bearing assembly together with a circuit block
diagram showing a conceptual construction of a detecting system
therefor;
FIG. 13 is a longitudinal sectional view of the sensor equipped
wheel support bearing assembly according to a fourth preferred
embodiment of the present invention;
FIG. 14 is a front elevational view of the outer member employed in
the wheel support bearing assembly, as viewed from the outboard
side;
FIG. 15 is a longitudinal sectional view of the sensor equipped
wheel support bearing assembly according to a fifth preferred
embodiment of the present invention;
FIG. 16 is a front elevational view of the outer member employed in
the wheel support bearing assembly, as viewed from the outboard
side;
FIG. 17 is a longitudinal sectional view of the sensor equipped
wheel support bearing assembly according to a sixth preferred
embodiment of the present invention;
FIG. 18 is a front elevational view of the outer member employed in
the wheel support bearing assembly, as viewed from the outboard
side;
FIG. 19 is a longitudinal sectional view of the sensor equipped
wheel support bearing assembly according to a seventh preferred
embodiment of the present invention;
FIG. 20 is a front elevational view of the outer member employed in
the wheel support bearing assembly, as viewed from the outboard
side;
FIG. 21A is a side view of the sensor unit employed in the wheel
support bearing assembly;
FIG. 21B is a rear view of the sensor unit;
FIG. 22 is an explanatory diagram showing a sectional view of the
wheel support bearing assembly together with a circuit block
diagram showing a conceptual construction of a detecting system
therefor;
FIG. 23 is a longitudinal sectional view of the sensor equipped
wheel support bearing assembly according to an eighth preferred
embodiment of the present invention;
FIG. 24 is a front elevational view of the outer member employed in
the wheel support bearing assembly, as viewed from the outboard
side;
FIG. 25 is a front elevational view of the outer member employed in
the wheel support bearing assembly according to a ninth preferred
embodiment of the present invention;
FIG. 26 is a front elevational view of the outer member employed in
the wheel support bearing assembly, as viewed from the outboard
side;
FIG. 27 is a longitudinal sectional view of the sensor equipped
wheel support bearing assembly according to a tenth preferred
embodiment of the present invention; and
FIG. 28 is a front elevational view of the outer member employed in
the wheel support bearing assembly, as viewed from the outboard
side.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The first preferred embodiment of the present invention will now be
described with particular reference to FIGS. 1 to 3. This
embodiment is applied to a wheel support bearing assembly for
rotatably supporting a vehicle drive wheel, which is an inner ring
rotating model of a third generation type. It is to be noted that
in the specification herein set forth, the term "outboard" is
intended to means one side of an automotive vehicle body away from
the longitudinal center of the automotive vehicle body, whereas the
term "inboard" is intended to means the opposite side of the
automotive vehicle body close towards the longitudinal center of
the automotive vehicle body.
The illustrated wheel support bearing device includes an outer
member 1 having an inner periphery formed with a plurality of rows
of raceway surfaces 3, an inner member 2 having raceway surfaces 4
formed in face-to-face relation with those raceway surfaces 3, and
a plurality of rows of rolling elements 5 interposed between the
raceway surfaces 3 in the outer member 1 and the raceway surfaces 4
in the inner member 2. The wheel support bearing device is rendered
to be of a double row, angular contact ball bearing type, and the
rolling elements 5 are employed in the form of a ball and supported
by respective retainers 6 one employed for each of the rows of the
rolling elements 5. The raceway surfaces 3 and 4 referred to above
have an arcuate shape in cross-section and are so formed as to
represent respective rolling element contact angles that are held
in back-to-back relation with each other. Opposite open ends of an
annular bearing space delimited between the outer member 1 and the
inner member 2 are sealed respectively by outboard and inboard
sealing units 7 and 8.
The outer member 1 serves as a stationary member and is of
one-piece construction having an outer periphery formed with a
vehicle body fitting flange 1a that is secured to a knuckle 25
forming a part of the automobile suspension system (not shown)
mounted on an automotive body structure. The flange 1a is provided
with vehicle body fitting holes 9, which are in the form of a screw
hole, at respective locations spaced in a direction
circumferentially thereof. The outer member 1 as viewed from the
outboard side is shown in a front elevational view in FIG. 2. As
shown therein, of the vehicle body fitting holes 9, the phase
difference .alpha. between the neighboring two vehicle body fitting
holes 9 remote from the road surface and the phase difference
.beta. between the neighboring two vehicle body fitting holes 9
adjacent the road surface are so chosen to be 80.degree. or more.
Fixing of the flange 1a to the knuckle 25 is carried out by the use
of knuckle bolts 26 each extending through a respective bolt
insertion hole 25a in the knuckle 25 and then firmly threaded into
an associated vehicle body fitting hole 9. It is to be noted that
each of the vehicle body fitting holes 9 in the vehicle body
fitting flange 1a may be a simplified bolt insertion hole and the
knuckle 25 may be fixedly secured to the vehicle body fitting
flange 1a with a nut fastened onto a corresponding knuckle bolt
26.
The inner member 2 serves as a rotatable member and is made up of a
hub axle 10 having an outer periphery formed with a wheel mounting
hub flange 10a, and an inner ring 11 mounted on an inboard end of
an axle portion 10b of the hub axle 10. The raceway surfaces 4 one
for each row are formed in the hub axle 10 and the inner ring 11,
respectively. The inboard end of the hub axle 10 has its outer
periphery provided with an inner ring mounting surface 12 which is
radially inwardly stepped to have a small diameter, and the inner
ring 11 is mounted on this inner ring mounting surface 12. The hub
axle 10 has a center bore 13 defined therein so as to extend
therethrough in a direction axially thereof. The hub flange 10a is
provided with a plurality of press-fitting holes 14 defined at
respective locations circumferentially thereof for receiving
corresponding hub bolts (not shown). At a portion of the hub axle
10 adjacent the root of the hub flange 10a, a cylindrical pilot
portion 15 for guiding a vehicle wheel and a brake component parts
(both not shown) protrudes towards the outboard side.
A sensor unit 16 is mounted on an inner periphery of an outboard
end of the outer member 1. The position where this sensor unit 16
is mounted is chosen to be between respective phases of the
neighboring two vehicle body fitting holes 9, which are remote from
the road surface and which are spaced from each other a distance
corresponding to a phase difference .alpha. of 80.degree. or more,
that is, a position corresponding to a circumferential position
sandwiched between the neighboring two vehicle body fitting holes
9, as shown in FIG. 2. The sensor unit 16 includes a sensor
mounting member 17 fixed to the inner periphery of the outer member
1 and a strain sensor 18 fitted to the sensor mounting member 17
and operable to measure a strain occurring in the sensor mounting
member 17.
As shown respectively in side and rear views in FIGS. 3A and 3B,
the sensor mounting member 17 is of a generally elongated, arcuate
shape extending along the outer member 1 and has opposite ends
formed with respective contact fixing portions 17a and 17b of an
arcuate shape protruding radially outwardly and, also extending in
a circumferential direction. This sensor mounting member 17 has an
intermediate portion formed with a recess 17c open at an outer
periphery thereof and a sensor 18 is fitted to a portion of an
inner periphery of the sensor mounting member 17 aligned with the
recess 17c. For example, the sensor mounting member 17 has a
rectangular shape in its cross section, but it may have any
suitable shape.
The sensor unit 16 referred to above is fixedly secured to the
outer member 1 through the contact fixing portions 17a and 17b in
the sensor mounting member 17. Fixing of the contact fixing
portions 17a and 17b to the outer member 1 is carried out by the
use of bolts or a bonding agent. It is to be noted that a gap is
formed between the sensor mounting member 17 and the outer member 1
except for respective portions of the sensor mounting member 17
that are occupied by the contact fixing portions 17a and 17b.
In the case of this embodiment, the sensor unit 16 is so arranged
and so positioned that one of the contact fixing portions, for
example, the contact fixing portion 17a, can occupy a zenith
position right above the longitudinal axis of the outer member 1
whereas the other contact fixing portion 17b occupies a position
spaced a few tens degrees from the zenith position in a
circumferential direction of the outer member 1. The zenith
position lying on the circumference of the outer member 1 is where
when an axially acting load is imposed on the outer member 1, the
outer member 1 can be most deformed in a radial direction thereof
whereas the position circumferentially spaced a few tens degrees
from the zenith position is where the outer member 1 can be
deformed in the radial direction thereof a quantity smaller than
that at the zenith position.
The sensor mounting member 17 is preferably of a kind which does
not plastically deform when an external force acting on the wheel
support bearing assembly or an working force acting between the
wheel tire and the road surface attains the highest expected value.
Accordingly, any one of metallic material such as, for example,
steel, copper, brass and aluminum can be suitably employed as
material for the sensor mounting member 17.
It is to be noted that the inboard sealing unit 8 is made up of a
seal element 8a, made of an elastic material such as, for example,
rubber, equipped with a core metal fitted to an inner peripheral
surface of the outer member 1, and a slinger 8b fitted to an outer
peripheral surface of the inner ring 10 and engageable with the
seal element 8a, and a magnetic encoder 19 for detecting the
rotation, which is in the form of a multipolar magnet having
magnetic poles alternating in a direction circumferentially
thereof, is mounted on the slinger 8b. Cooperable with this
magnetic encoder 19 is a magnetic sensor 20 that is fitted to the
outer member 1 in face-to-face relation with the magnetic encoder
19.
As shown in FIG. 4, as a means for processing an output from the
sensor unit 16, a circuit unit is provided, which includes an
external force calculating module 21, a road surface derived force
calculating module 22, a bearing preload amount calculating module
23 and an abnormality determining module 24. This circuit unit
including those modules 21 to 24 may be incorporated in an
electronic circuit device (not shown) such as, for example, a
circuit substrate fitted to the outer member 1 or the like of the
wheel support bearing assembly, or in an electric control unit
(ECU) mounted on the automotive vehicle.
The operation of the sensor equipped wheel support bearing assembly
of the structure described hereinabove will now be described. When
a load is applied to the hub axle 10, the outer member 1 is
deformed through the rolling elements 5 and this deformation is
transmitted to the sensor mounting member 17 of the sensor unit 16,
fitted to the inner periphery of the outer member 1, resulting in a
corresponding deformation of the sensor mounting member 17. This
strain occurring in the sensor mounting member 17 is measured by
the strain sensor 18. At this time, the sensor mounting member 17
deforms accompanying deformation of the fixing portion of the
sensor mounting member 17 in the radial direction, but since the
sensor mounting member 17 is fitted to the position where it can be
most deformed in the radial direction, the strain of the sensor
mounting member 17 becomes so considerable that even the slightest
strain of the outer member 1, which is the stationary member, can
be detected by the sensor unit 16. In addition, since the sensor
mounting member 17 is provided with the recess 17c and the rigidity
at the position where the recess 17c is formed is lowered, more
considerable strain than the strain of the outer member 1 occurs in
the sensor mounting member 17 and, accordingly, even the slightest
strain of the outer member 1 can be more accurately detected with
the strain sensor 18.
In general, the wheel support bearing assembly has various
component parts of high rigidity in order to secure the performance
thereof. Since for this reason, the strain occurring in the
stationary member is small, difficulty is often encountered in
detecting the working force acting between the wheel tire and the
road surface with the sensor unit 16. In this respect, in the first
embodiment now under discussion, since the phase difference .alpha.
between the neighboring two vehicle body fitting holes 9 adjacent
the road surface, out from the vehicle body fitting holes 9 formed
in the outer member 1, is so chosen as to be 80.degree. or more and
the sensor unit 16 is fitted in position between those two
neighboring vehicle body fitting holes 9 that are spaced a distance
corresponding to such phase difference of 80.degree. or more, the
strain of the sensor mounting member 17 is so considerable that
even the slightest strain occurring in the outer member 1 can be
detected with the sensor unit 16.
Since of the two contact fixing portions 17a and 17b in the sensor
mounting member 17, one contact fixing portion 17a is positioned at
the zenith position lying on the entire circumference, where the
outer member 1 is most deformed in the radial direction in response
to the load acting on the outer member 1, and the other contact
fixing portion 17b is held at a position spaced a few tens degrees
from the zenith position in the circumferential direction, where
the outer member 1 can be deformed in the radial direction thereof
a quantity smaller than that at the zenith position, a further
considerable strain occurs in a portion of the sensor mounting
member 17, where the strain sensor 18 is mounted when the first
contact fixing portion 17a undergoes a considerable deformation
with the second contact fixing portion 17b providing the fulcrum,
and, accordingly, the strain of the outer member 1 can be detected
by the strain sensor 18 with high sensitivity.
From the value of strain so detected in the manner described above,
it is possible to detect the external force or the like acting on
the wheel support bearing assembly. Since change in strain varies
depending on the direction and the magnitude of the load, the
external force acting on the wheel support bearing assembly or the
working force acting between the wheel tire and the road surface
can be calculated if the relation between the strain and the load
is determined beforehand by means of a series of experiments or
simulations. The external force calculating module 21 and the road
surface derived force calculating module 22 are operable in
response to the output from the strain sensor 18 to calculate the
external force acting on the wheel support bearing assembly and the
working force acting between the wheel tire and the road surface,
respectively, in reference to the relation between the strain and
the load so determined beforehand by means of the experiments or
simulations.
The abnormality determining module 24 is operable to output an
abnormality signal to the outside in the event that the working
force acting between the wheel tire and the road surface or the
external force acting on the wheel support bearing assembly so
calculated is determined as exceeding a predetermined allowance.
This abnormality signal can be utilized in vehicle control of the
automotive vehicle.
Also, if the external force acting on the wheel support bearing
assembly or the working force acting between the wheel tire and the
road surface is outputted in real time by the external force
calculating module 21 and the road surface derived force
calculating module 22, a sophisticated vehicle control can be
accomplished.
Also, while the wheel support bearing assembly is applied a preload
through the inner ring 11, the sensor mounting member 17 will
deform even under the influence of such preload. For this reason,
if the relation between the strain and the preload is determined
beforehand by means of a series of experiments or simulations, it
is possible to ascertain the condition of preload in the wheel
support bearing assembly. The bearing preload amount calculating
module 23 is operable in response to an output from the strain
sensor 18 to output a bearing preload amount in reference to the
relation between the strain and the preload so determined
beforehand by means of the experiments or simulations. Also, if the
preload amount outputted from the bearing preload amount
calculating module 23 is utilized, adjustment of the preload during
assemblage of the wheel support bearing assembly can be
facilitated.
In the foregoing first embodiment, although the sensor unit 16 is
disposed on that portion of the inner periphery of the outer member
1, where the neighboring vehicle body fitting holes 9 in the outer
member 1 remote from the road surface are spaced from each other a
distance corresponding to the phase difference .alpha., the sensor
unit 16 may be disposed on a portion of the inner periphery of the
outer member 1, where the neighboring vehicle body fitting holes 9
adjacent the road surface are spaced from each other a distance
corresponding to the phase difference .beta..
Also, as shown in FIG. 5, the sensor unit 16 may be disposed on
that portion of the inner periphery of the outer member 1, where
the neighboring vehicle body fitting holes 9 remote from the road
surface are spaced from each other a distance corresponding to the
phase difference .alpha. and, also, on a portion of the inner
periphery of the outer member 1, where the neighboring vehicle body
fitting holes 9 adjacent the road surface are spaced from each
other a distance corresponding to the phase difference .beta..
Yet, each of the sensor units 16 shown in FIG. 5 may be so
structured as to have three contact fixing portions 17a, 17b and
17d and two recesses 17c and 17e one positioned between the
neighboring contact fixing portions 17a and 17b and other
positioned between the neighboring contact fixing portions 17a and
17d and opening at the outer periphery of the respective sensor
units 16 as shown in FIG. 6.
In addition, each of the sensor unit 16 may be disposed on an outer
periphery of the outer member 1 such as shown in a second preferred
embodiment in FIGS. 7 and 8. In such case, the contact fixing
portions 17a and 17b of the sensor mounting member 17 are of an
arcuate shape protruding radially inwardly and, also extending in a
circumferential direction, with the respective recesses 17c opening
radially inwardly of the arcuate shape of the sensor mounting
member 17.
In any of those first and second embodiments, it is necessary to
design and shape the sensor mounting member 17 which does not
undergo a plastic deformation even when the maximum expected load
is imposed on the wheel support bearing assembly.
In the following description, a third preferred embodiment of the
present invention will be described with particular reference to
FIGS. 9 to 11. Even this embodiment is applied to the wheel support
bearing assembly for the support of a vehicle drive wheel, which is
an inner ring rotating model of a third generation type. It is to
be noted that even in this embodiment, one side of an automotive
vehicle body away from the longitudinal center of the automotive
vehicle body is referred to as "outboard", and the opposite side of
the automotive vehicle body close towards the longitudinal center
of the automotive vehicle body is referred to as "inboard".
This wheel support bearing assembly includes an outer member 101
having an inner periphery formed with a plurality of rows of
raceway surfaces 103, an inner member 102 formed with raceway
surfaces 104 held in face-to-face relation with the raceway
surfaces 103, and a plurality of rows of rolling elements 105
interposed between the respective raceway surfaces 103 and 104 in
the outer member 101 and the inner member 102. The wheel support
bearing device is rendered to be of a double row, angular contact
ball bearing type, and the rolling elements 105 are employed in the
form of a ball and supported by respective retainers 106 one
employed for each of the rows of the rolling elements 105. The
raceway surfaces 103 and 104 referred to above have an arcuate
shape in cross-section and are so formed as to represent respective
rolling element contact angles that are held in back-to-back
relation with each other. Opposite open ends of an annular bearing
space delimited between the outer member 101 and the inner member
102 are sealed respectively by outboard and inboard sealing units
107 and 108.
The outer member 101 serves as a stationary member and is of
one-piece construction having an outer periphery formed with a
vehicle body fitting flange 101a that is secured to a knuckle
forming a part of the automobile suspension system (not shown)
mounted on an automotive body structure. The flange 101a is
provided with vehicle body fitting holes 109 at respective
locations spaced in a direction circumferentially thereof.
The inner member 102 serves as a rotatable member and is made up of
a hub axle 110 having an outer periphery formed with a wheel
mounting hub flange 110a, and an inner ring 111 mounted on an
inboard end of an axle portion 110b of the hub axle 110. The
raceway surfaces 104 one for each row are formed in the hub axle
110 and the inner ring 111, respectively. The inboard end of the
hub axle 110 has its outer periphery provided with an inner ring
mounting surface 112 which is radially inwardly stepped to have a
small diameter, and the inner ring 111 is mounted on this inner
ring mounting surface 112. The hub axle 110 has a center bore 113
defined therein so as to extend therethrough in a direction axially
thereof. The hub flange 110a is provided with a plurality of
press-fitting holes 114 defined at respective locations
circumferentially thereof for receiving corresponding hub bolts
(not shown). At a portion of the hub axle 110 adjacent the root of
the hub flange 110a, a cylindrical pilot portion 115 for guiding a
vehicle wheel and a brake component parts (both not shown)
protrudes towards the outboard side.
A sensor unit 116 is mounted on an inner periphery of an outboard
end of the outer member 101. The axial position of the sensor unit
116 is rendered to be on an outboard side of the outboard raceway
surface 104 in the outer member 101 and on an inboard side of the
outboard sealing unit 107. The outer member 101 as viewed from the
outboard side is shown in FIG. 10 in a front elevational view. As
shown therein, the sensor unit 116 includes a mounting member 117,
made of a magnetostrictive material and fixed on an outer
peripheral surface of the outer member 101, and a detecting coil
118 mounted on this mounting member 117 for measuring an inverse
magnetostrictive effect of the mounting member 117.
The mounting member 117 is of a shape and made of a material, which
does not undergo plastic deformation when fixed. In this third
embodiment, the mounting member 117 is, a shown in side and rear
views in FIGS. 11A and 11B, respectively, of an elongated,
substantially arcuate shape curved to follow the circumference of
the outer member 101 and has its opposite ends formed with
respective contact fixing portions 117a and 117b protruding in a
direction radially inwardly from the arcuate shape and, also, in a
laterally widthwise direction. This mounting member 117 has an
intermediate portion formed with a recess 117c open at an inner
periphery thereof and the detecting coil 118 is wound around and
fitted to the recess 117c. For example, the mounting member 117 has
a rectangular shape in its cross section, but it may have any
suitable shape.
The sensor unit 116 referred to above is fixedly secured to an
outer peripheral surface of the outer member 101 through the
contact fixing portions 117a and 117b of the mounting member 117,
with the lengthwise direction of the mounting member 117 oriented
in a direction circumferentially of the outer member 101. Fixing of
the contact fixing portions 117a and 117b to the outer member 101
is carried out by the use of bolts or a bonding agent. It is to be
noted that a gap is formed between the mounting member 117 and the
outer member 101 except for respective portions of the mounting
member 117 that are occupied by the contact fixing portions 117a
and 117b.
In the case of this third embodiment, the sensor unit 116 is so
arranged and so positioned that one of the contact fixing portions,
for example, the contact fixing portion 117a, can occupy a zenith
position on the circumference of the outer member 101, which is
right above the longitudinal axis of the outer member 101, whereas
the other contact fixing portion 117b occupies a position spaced a
few tens degrees from the zenith position in a circumferential
direction of the outer member 101. The zenith position lying on the
circumference of the outer member 101 is where when an axially
acting load is imposed on the outer member 101, the outer member
101 can be most deformed in a radial direction thereof whereas the
position circumferentially spaced a few tens degrees from the
zenith position is where the outer member 101 can be deformed in
the radial direction thereof a quantity smaller than that at the
zenith position.
The mounting member 117 is preferably of a kind which does not
plastically deform when an external force acting on the wheel
support bearing assembly or a working force acting between the
wheel tire and the road surface attains the highest expected value.
Once the plastic deformation occurs, deformation of the outer
member 101 will not be accurately transmitted to the mounting
member 117 and measurement of the inverse magnetostrictive effect
will be affected adversely. For the mounting member 117, some
materials are available and Ni or the like having a negative
magnetostrictive constant can be suitably employed as it can enable
measurement with high sensitivity. Also, where the material forming
the mounting member 117 is chosen to be the same as that forming
the outer member 101, it is possible to minimize influences brought
about by temperature on the detecting accuracy.
It is to be noted that the inboard sealing unit 108 includes a
sealing member 108a made of an elastic material such as, for
example, rubber equipped with a core metal fitted to the inner
peripheral surface of the outer member 101, and a slinger 108b
fitted to the outer peripheral surface of the inner ring 10 and
engageable with the sealing member 108a, and a magnetic encoder 119
for the detection of the rotation, which is in the form of a
multipolar magnet having magnetic poles alternating in a direction
circumferentially thereof, is provided in the slinger 108a.
Cooperable with the magnetic encoder 119 is a magnetic sensor (not
shown) mounted on the outer member 101 in face-to-face relation
therewith.
As shown in FIG. 12, as a means for processing an output from the
sensor unit 116, a circuit unit is provided, which includes an
external force calculating module 121, a road surface derived force
calculating module 122, a bearing preload amount calculating module
123 and an abnormality determining module 124. This circuit unit
including those modules 121 to 124 may be incorporated in an
electronic circuit device (not shown) such as, for example, a
circuit substrate fitted to the outer member 101 or the like of the
wheel support bearing assembly, or in an electric control unit
(ECU) mounted on the automotive vehicle.
The operation of the sensor equipped wheel support bearing assembly
of the structure described hereinabove will now be described. When
a load is applied to the hub axle 110, the outer member 101 is
deformed through the rolling elements 105 and this deformation is
transmitted to the mounting member 117, fitted to the outer
periphery of the outer member 101, resulting in a corresponding
deformation of the sensor mounting member 117. The inverse
magnetostrictive effect of the recess 117c in the mounting member
117 is measured by the detected by the detecting coil 118. At this
time, the mounting member 117 deforms accompanying deformation of
the fixing portion of the mounting member 117 in the radial
direction, but since the mounting member 117 is fitted to the
position where it can be most deformed in the radial direction, the
strain of the mounting member 117 becomes so considerable that even
the slightest strain of the outer member 101, which is the
stationary member, can be detected by the sensor unit 116. In
addition, since the mounting member 117 is of an arcuate shape and
is provided with the recess 117c and the rigidity at the position
where the recess 117c is formed is lowered, more considerable
strain than the strain of the outer member 101 occurs in the
mounting member 117 and, accordingly, the strain of the outer
member 101 can be detected as a considerable inverse
magnetostrictive effect.
Also, since of the two contact fixing portions 117a and 117b in the
sensor mounting member 117, the first contact fixing portion 117a
is positioned at the zenith position lying on the entire
circumference, where the outer member 101 is most deformed in the
radial direction in response to the load acting on the outer member
101, and the second contact fixing portion 117b is held at a
position spaced a few tens degrees from the zenith position in the
circumferential direction, where the outer member 101 can be
deformed in the radial direction thereof a quantity smaller than
that at the zenith position, a further considerable strain occurs
in a portion of the mounting member 117, where the detecting coil
118 is mounted when the first contact fixing portion 117a undergoes
a considerable deformation with the second contact fixing portion
117b providing the fulcrum, and, accordingly, the strain of the
outer member 101 can be detected by the detecting coil 118 as the
considerable inverse magnetostrictive effect.
It is to be noted that, of the contact fixing portions 117a and
117b, the second contact fixing portion 117b may be positioned at a
location where the direction of the radially induced strain brought
about by the external force acting on the outer member 101 or the
working force acting between the wheel tire and the road surface is
reverse to that occurring in the first contact fixing portion 117.
By way of example, the direction of the radially induced
deformation of the outer member 101 relative to the axially acting
load, acting on a point of contact between the wheel tire and the
road surface, at a position above the right transverse position
(position 90.degree. above the position adjacent the road surface)
of the outer member 101 is reverse to that at a position below the
right transverse position (position adjacent the road surface).
Assuming that the second contact fixing portion 117b is held at the
position below the right transverse position of the outer member
101 where the first contact fixing portion 117a is held at the
position (position remote from the road surface) right above the
outer member 101, respective directions of deformation of the outer
member 101 in the first and second contact fixing portions 117a and
117b are reverse to each other. As discussed above, if the second
contact fixing portion 117b and the first contact fixing portion
117a are where the radially induced strain of the outer member 101
occurs in the respective directions reverse to each other, the
strains in those directions can be summed up and the more
considerable deformation of the outer member 101 can be transmitted
to the mounting member 117 and the more considerable deformation
can be detected, enabling the strain of the outer member 101 to be
detected with higher sensitivity.
The axial position of the outer member 101, where the sensor unit
116 is fitted, may be a position on the outboard side of the
outboard raceway surface 103 in the outer member 101 such as in the
third embodiment, a position intermediate between the raceway
surfaces 103 and 103, or on the inboard side of the inboard raceway
surface 103, but the position on the outboard side of the outboard
raceway surface 103 is effective to enable detection of the load in
the directions reverse to each other since the strain can have a
directionality depending on the direction of the load.
According to the FEM analysis and results of experiments, with
respect to both of the radially induced strain and the
circumferentially induced strain of the outer member 101, the
strain could have a directionality in a positive sign or a negative
sign in dependence on the positive sign or negative sign of the
load such as, for example, the external force or the force, both
referred to previously, occurs in a portion on the outboard side
out of the 103 locations in the outer member 101. Accordingly, in
order to detect the positive or negative direction of the load, it
is necessary for the sensor unit 116 to be mounted on the outboard
position in the outer member 101.
Where the sensor unit 116 is fitted to the outboard position, since
the strain on one side of the zenith position in the
circumferential direction and that on the other side of the zenith
position in the circumferential direction are opposite or reverse
to each other and, therefore, the strain can be detected with high
sensitivity even when the first contact fixing portion 117a and the
second contact fixing portion 117b are arranged on respective sides
of the zenith position.
From the value of the inverse magnetostrictive effect so measured
as hereinabove described, the external force or the like acting on
the wheel support bearing assembly can be detected. Since the
inverse magnetostrictive effect changes differently depending on
the direction and the magnitude of the load, if the relation
between the inverse magnetostrictive effect and the load is
determined beforehand by means of a series of experiments or
simulations, the external force acting on the wheel support bearing
assembly or the working force acting between the wheel tire and the
road surface can be calculated. The external force calculating
module 121 and the road surface derived force calculating module
122 are operable in response to the output from the detecting coil
118 to calculate the external force acting on the wheel support
bearing assembly and the working force acting between the wheel
tire and the road surface, respectively, in reference to the
relation between the inverse magnetostrictive effect and the load
so determined beforehand by means of the experiments or
simulations.
The abnormality determining module 124 is operable to output an
abnormality signal to the outside in the event that the working
force acting between the wheel tire and the road surface or the
external force acting on the wheel support bearing assembly so
calculated is determined as exceeding a predetermined allowance.
This abnormality signal can be utilized in vehicle control of the
automotive vehicle.
Also, if the external force acting on the wheel support bearing
assembly or the working force acting between the wheel tire and the
road surface is outputted in real time by the external force
calculating module 121 and the road surface derived force
calculating module 122, a sophisticated vehicle control can be
accomplished.
Also, while the wheel support bearing assembly is applied a preload
through the inner ring 111, the mounting member 117 will deform
even under the influence of such preload. For this reason, if the
relation between the inverse magnetostrictive effect and the
preload is determined beforehand by means of a series of
experiments or simulations, it is possible to ascertain the
condition of preload in the wheel support bearing assembly. The
bearing preload amount calculating module 123 is operable in
response to an output from the detecting coil 118 to output a
bearing preload amount in reference to the relation between the
inverse magnetostrictive effect and the preload so determined
beforehand by means of the experiments or simulations. Also, if the
preload amount outputted from the bearing preload amount
calculating module 123 is utilized, adjustment of the preload
during assemblage of the wheel support bearing assembly can be
facilitated.
In the third embodiment described above, although the sensor unit
116 has been shown and described as mounted on a portion of the
outer peripheral portion of the outer member 101 remote from the
road surface, the sensor unit 116 may be mounted on a portion of
the outer peripheral surface of the outer member 101 adjacent the
road surface.
Also, as shown in a fourth preferred embodiment shown in FIGS. 13
and 14, the sensor unit 116 may be mounted not only on a portion of
the outer peripheral surface of the outer member 101 remote from
the road surface, but on a portion of the outer peripheral surface
of the outer member 101 adjacent the road surface. Where the two or
more sensor units 116 are so arranged as hereinabove described, it
is possible to detect the load with high accuracy.
Yet, each of the sensor units 116 shown in FIGS. 13 and 14 may be
of a structure including, as shown in a fifth preferred embodiment
of the present invention in FIGS. 15 and 16, three contact fixing
portions 117a, 117b and 117d and recesses 117c, 117e positioned
between the contact fixing portions 117a and 117b and between the
contract fixing portions 117a and 117d, respectively, with the
recesses 117c opening radially outwardly of the arcuate shape.
Where it is difficult to use a plurality of sensor units 116 by
reason of, for example, unavailability of the space, if the
mounting member 117 is so structured and so configured as described
above, the plurality of the sensor units 116 can easily be
installed and a further accurate detection of the load will become
possible.
In addition, in a sixth preferred embodiment of the present
invention shown in FIGS. 17 and 18, the sensor unit 16 may be
arranged on the inner peripheral surface of the outer member 101.
In this case, the contact fixing portions 117a and 117b of the
mounting member 117 are of an arcuate shape protruding radially
outwardly and, also extending in a circumferential direction, with
the recess 117 opening towards the outer periphery of the arcuate
shape.
In each of the third to sixth preferred embodiments of the present
invention, the mounting member 117 should have such a shape that no
plastic deformation occur therein even when the maximum expected
load is applied to the wheel support bearing assembly.
Hereinafter, a seventh preferred embodiment of the present
invention will be described with particular reference to FIGS. 19
to 21. Even this embodiment is applied to the wheel support bearing
assembly for the support of a vehicle drive wheel, which is an
inner rotating model of a third generation type. It is to be noted
that even in this embodiment, one side of an automotive vehicle
body away from the longitudinal center of the automotive vehicle
body is referred to as "outboard", and the opposite side of the
automotive vehicle body close towards the longitudinal center of
the automotive vehicle body is referred to as "inboard".
This wheel support bearing assembly includes an outer member 201
having an inner periphery formed with a plurality of rows of
raceway surfaces 203, an inner member 202 formed with raceway
surfaces 204 held in face-to-face relation with the raceway
surfaces 203, and a plurality of rows of rolling elements 205
interposed between the respective raceway surfaces 203 and 204 in
the outer member 201 and the inner member 202. The wheel support
bearing device is rendered to be of a double row, angular contact
ball bearing type, and the rolling elements 205 are employed in the
form of a ball and supported by respective retainers 206 one
employed for each of the rows of the rolling elements 205. The
raceway surfaces 203 and 204 referred to above have an arcuate
shape in cross-section and are so formed as to represent respective
rolling element contact angles that are held in back-to-back
relation with each other. Opposite open ends of an annular bearing
space delimited between the outer member 201 and the inner member
202 are sealed respectively by outboard and inboard sealing units
207 and 208.
The outer member 201 serves as a stationary member and is of
one-piece construction having an outer periphery formed with a
vehicle body fitting flange 201 a that is secured to a knuckle
forming a part of the automobile suspension system (not shown)
mounted on an automotive body structure. The flange 201a is
provided with vehicle body fitting holes 209 at respective
locations spaced in a direction circumferentially thereof.
The inner member 202 serves as a rotatable member and is made up of
a hub axle 210 having an outer periphery formed with a wheel
mounting hub flange 210a, and an inner ring 211 mounted on an
inboard end of an axle portion 210b of the hub axle 210. The
raceway surfaces 204 one for each row are formed in the hub axle
210 and the inner ring 211, respectively. The inboard end of the
hub axle 210 has its outer periphery provided with an inner ring
mounting surface 212 which is radially inwardly stepped to have a
small diameter, and the inner ring 211 is mounted on this inner
ring mounting surface 212. The hub axle 210 has a center bore 213
defined therein so as to extend therethrough in a direction axially
thereof. The hub flange 210a is provided with a plurality of
press-fitting holes 214 defined at respective locations
circumferentially thereof for receiving corresponding hub bolts
(not shown). At a portion of the hub axle 210 adjacent the root of
the hub flange 210a, a cylindrical pilot portion 215 for guiding a
vehicle wheel and a brake component parts (both not shown)
protrudes towards the outboard side.
A sensor unit 216 is mounted on an inner periphery of an outboard
end of the outer member 201. The axial position of the sensor unit
216 is rendered to be on an outboard side of the outboard raceway
surface 204 in the outer member 101 and on an inboard side of the
inboard sealing unit 207. The outer member 201 as viewed from the
outboard side is shown in FIG. 20 in a front elevational view. As
shown therein, the sensor unit 216 includes a sensor mounting
member 217 fixed on an outer peripheral surface of the outer member
201, and a displacement sensor 218 mounted on this sensor mounting
member 217 for measuring a relative displacement between the sensor
mounting member 217 and the stationary member. The displacement
sensor 218 may be employed in the form of an eddy current sensor, a
magnetic sensor, an optical sensor, an ultrasonic sensor or a
contact type sensor.
The sensor mounting member 217 is of a shape and made of a
material, which does not undergo plastic deformation when fixed. In
this seventh embodiment, the sensor mounting member 217 is, a shown
in side and rear views in FIGS. 21A and 11B, respectively, of an
elongated, substantially arcuate shape curved to follow the
circumference of the outer member 201 and has its opposite ends
formed with respective contact fixing portions 217a and 217b of an
arcuate shape protruding radially inwardly and, also extending in a
circumferential direction. The displacement sensor 218 is mounted
on an intermediate portion of the sensor mounting member 217 so as
to extend radially thereacross. For example, the sensor mounting
member 217 has a rectangular shape in its cross section, but it may
have any suitable shape.
The sensor unit 216 referred to above is fixedly secured to an
outer peripheral surface of the outer member 201 through the
contact fixing portions 217a and 217b of the sensor mounting member
217, with the lengthwise direction of the sensor mounting member
217 oriented in a direction circumferentially of the outer member
201. Fixing of the contact fixing portions 217a and 217b to the
outer member 201 is carried out by the use of bolts or a bonding
agent. It is to be noted that a gap is formed between the sensor
mounting member 217 and the outer member 201 except for respective
portions of the sensor mounting member 217 that are occupied by the
contact fixing portions 217a and 217b.
In the case of this seventh embodiment, the contact fixing portions
217a and 217b are positioned at respective locations spaced a few
tens degree leftwards and rightwards from the zenith position
(position remote from the road surface) on the entire circumference
of the outer member 201 and the sensor unit 216 is so arranged that
the position of the sensor mounting member 217, where the
displacement sensor 218 is mounted, can occupy the zenith position
referred to above. The zenith position lying on the entire
circumference of the outer member 201 is where when an axially
acting load is imposed on the outer member 201, the outer member
201 can be most deformed in a radial direction thereof whereas the
position circumferentially spaced a few tens degrees from the
zenith position is where the outer member 201 can be deformed in
the radial direction thereof a quantity smaller than that at the
zenith position.
The sensor mounting member 217 is preferably of a kind which does
not plastically deform when an external force acting on the wheel
support bearing assembly or a working force acting between the
wheel tire and the road surface attains the highest expected value.
Once the plastic deformation occurs, deformation of the outer
member 201 will not be accurately transmitted to the sensor
mounting member 217 and measurement of the displacement of the
outer member 201 by the displacement sensor 218 will be affected
adversely. If the sensor mounting member 217 is made of the same
material as that for the outer member 201, it is possible to
minimize temperature dependent influences on the detecting
accuracy.
It is to be noted that the inboard sealing unit 208 includes a
sealing member 208a made of an elastic material such as, for
example, rubber equipped with a core metal fitted to the inner
peripheral surface of the outer member 201, and a slinger 208b
fitted to the outer peripheral surface of the inner ring 210 and
engageable with the sealing member 208a, and a magnetic encoder 219
for the detection of the rotation, which is in the form of a
multipolar magnet having magnetic poles alternating in a direction
circumferentially thereof, is provided in the slinger 208b.
Cooperable with the magnetic encoder 219 is a magnetic sensor (not
shown) mounted on the outer member 201 in face-to-face relation
therewith.
As shown in FIG. 22, as a means for processing an output from the
sensor unit 216, a circuit unit is provided, which includes an
external force calculating module 221, a road surface derived force
calculating module 222, a bearing preload amount calculating module
223 and an abnormality determining module 224. This circuit unit
including those modules 221 to 224 may be incorporated in an
electronic circuit device (not shown) such as, for example, a
circuit substrate fitted to the outer member 201 or the like of the
wheel support bearing assembly, or in an electric control unit
(ECU) mounted on the automotive vehicle.
The operation of the sensor equipped wheel support bearing assembly
of the structure described hereinabove will now be described. When
a load is applied to the hub axle 210, the outer member 201 is
deformed through the rolling elements 205 and this deformation is
transmitted to the mounting member 217, fitted to the inner
periphery of the outer member 201, resulting in a corresponding
deformation of the sensor mounting member 217. Accordingly, the
radial distance between the outer member 201 and the sensor
mounting member 217 changes and the displacement sensor 218
measures such change in distance. At this time, since portions of
the outer member 201, where the contact fixing portions 217a and
217b of the sensor mounting member 217 are secured (respective
positions spaced a few tens degrees leftwards and rightwards from
the zenith position in the circumferential direction) do not deform
in the radial direction, but a portion of the outer member 201 at
the zenith position confronting the position where the displacement
sensor 218 is arranged deforms considerably in the radial
direction, the radial distance between the outer peripheral surface
of the outer member 201 and the position of the sensor mounting
member 217, where the displacement sensor 218 is mounted, changes
considerably in response to such deformation in the radial
direction and, accordingly, even the slightest strain occurring in
the outer member 201, which is the stationary member, can be
detected with the sensor unit 216.
The axial position of the outer member 201, where the sensor unit
216 is fitted, may be a position on the outboard side of the
outboard raceway surface 203 in the outer member 201 such as in the
seventh embodiment, a position intermediate between the raceway
surfaces 203 and 203, or on the inboard side of the inboard raceway
surface 203, but the position on the outboard side of the outboard
raceway surface 203 is effective to enable detection of the load in
the directions reverse to each other since the strain can have a
directionality depending on the direction of the load.
According to the FEM analysis and results of experiments, with
respect to both of the radially induced strain and the
circumferentially induced strain of the outer member 201, the
strain could have a directionality in a positive sign or a negative
sign in dependence on the positive sign or negative sign of the
load such as, for example, the external force or the force, both
referred to previously, occurs in a portion on the outboard side
out of the three locations in the outer member 201. Accordingly, in
order to detect the positive or negative direction of the load, it
is necessary for the sensor unit 216 to be mounted on the outboard
position in the outer member 201.
From the value of the displacement of the outer member 201 (the
radial distance between the outer member 201 and the sensor
mounting member 217) so measured as hereinabove described, the
external force or the like acting on the wheel support bearing
assembly can be detected. Since the amount of displacement varies
differently depending on the direction and the magnitude of the
load, if the relation between the amount of displacement and the
load is determined beforehand by means of a series of experiments
or simulations, the external force acting on the wheel support
bearing assembly or the working force acting between the wheel tire
and the road surface can be calculated. The external force
calculating module 221 and the road surface derived force
calculating module 222 are operable in response to the output from
the displacement sensor 218 to calculate the external force acting
on the wheel support bearing assembly and the working force acting
between the wheel tire and the road surface, respectively, in
reference to the relation between the amount of displacement and
the load so determined beforehand by means of the experiments or
simulations.
The abnormality determining module 224 is operable to output an
abnormality signal to the outside in the event that the working
force acting between the wheel tire and the road surface or the
external force acting on the wheel support bearing assembly so
calculated is determined as exceeding a predetermined allowance.
This abnormality signal can be utilized in vehicle control of the
automotive vehicle.
Also, if the external force acting on the wheel support bearing
assembly or the working force acting between the wheel tire and the
road surface is outputted in real time by the external force
calculating module 221 and the road surface derived force
calculating module 222, a sophisticated vehicle control can be
accomplished.
Also, while the wheel support bearing assembly is applied a preload
through the inner ring 211, the sensor mounting member 217 will
deform even under the influence of such preload. For this reason,
if the relation between the amount of displacement and the preload
is determined beforehand by means of a series of experiments or
simulations, it is possible to ascertain the condition of preload
in the wheel support bearing assembly. The bearing preload amount
calculating module 223 is operable in response to an output from
the displacement sensor 218 to output a bearing preload amount in
reference to the relation between the amount of displacement and
the preload so determined beforehand by means of the experiments or
simulations. Also, if the preload amount outputted from the bearing
preload amount calculating module 223 is utilized, adjustment of
the preload during assemblage of the wheel support bearing assembly
can be facilitated.
In the seventh embodiment described above, although the sensor unit
216 has been shown and described as mounted on a portion of the
outer peripheral portion of the outer member 201 remote from the
road surface, the sensor unit 216 may be mounted on a portion of
the outer peripheral surface of the outer member 201 adjacent the
road surface.
Also, as shown in an eighth preferred embodiment shown in FIGS. 23
and 24, the sensor unit 216 may be mounted each of respective
portions of the outer peripheral surface of the outer member 201
remote from and adjacent to the road surface, where different
degrees of change in deformation in the radial direction occur.
Where the two or more sensor units 216 are so arranged as
hereinabove described, it is possible to detect the load with high
accuracy.
Yet, each of the sensor units 216 shown in FIGS. 23 and 24 may be
of a structure including, as shown in a ninth preferred embodiment
of the present invention in FIGS. 25 and 26, three contact fixing
portions 217a, 217b and 217d and two displacement sensors 218
positioned between the contact fixing portions 217a and 217b and
between the contract fixing portions 217b and 217c, respectively.
Where it is difficult to use a plurality of sensor units 216 by
reason of, for example, unavailability of the space, if the sensor
mounting member 217 is so structured and so configured as described
above, the plurality of the sensor units 216 can easily be
installed and a further accurate detection of the load will become
possible.
In addition, in a tenth preferred embodiment of the present
invention shown in FIGS. 27 and 28, the sensor unit 216 may be
arranged on the inner peripheral surface of the outer member 201.
In this case, the contact fixing portions 217a and 217b of the
sensor mounting member 217 are of an arcuate shape protruding
radially outwardly and, also extending in a circumferential
direction.
In each of the seventh to tenth preferred embodiments of the
present invention, the sensor mounting member 217 should have such
a shape that no plastic deformation occur therein even when the
maximum expected load is applied to the wheel support bearing
assembly.
Although in describing any one of the foregoing embodiments of the
present invention, the outer member has been shown and described as
serving the stationary member, the present invention can be applied
to the wheel support bearing assembly, in which the inner member
serves as the stationary member. In such case, the sensor mounting
member 17 or 217 or the mounting member 117 has to be fitted to the
peripheral surface which will become an outer periphery or an inner
periphery of the inner member.
Also, although any one of the foregoing embodiments of the present
invention has been shown and described as applied to the wheel
support bearing assembly of the third generation type, the present
invention can be equally applied to the wheel support bearing
assembly of the first or the second generation type, in which the
bearing unit and the hub are constituted by members separate from
each other, respectively, and also to the wheel support bearing
assembly of the fourth generation type, in which a portion of the
inner member is constituted by an outer ring of the constant
velocity joint. Yet, this wheel support bearing assembly can be
applied to the wheel support bearing assembly for the support of
the coupled driving wheel (the non-drive wheel) and, also, to the
wheel support bearing assembly of any generation type, in which the
rolling elements are employed in the form of a tapered roller.
Hereinafter, some possible aspects will be demonstrated, which
utilize any one of the sensor equipped wheel bearing assemblies
according to the fourth to seventh aspects, respectively, or any
one of the sensor equipped wheel support bearing assemblies
according to the first, eighth and ninth aspects, respectively, and
which will form a preferred embodiment of the present
invention.
[11th Aspect]
The sensor equipped wheel support bearing assembly according to any
one of the fourth to seventh aspects, in which the sensor unit is
employed in a plural number.
In other words, the sensor unit referred to above may be in a
plural number. Since if the sensor unit is in a plural number,
strains occurring at a plurality of locations of the stationary
member can be detected by the plural detecting coils and the load
or the like acting on the vehicle wheel can be detected from
respective outputs from the plural detecting coils, the accuracy of
detection of the load or the like acting on the vehicle wheel can
be increased.
[12th Aspect]
The sensor equipped wheel support bearing assembly according to any
one of the fourth to seventh and eleventh aspects referred to
above, in which the sensor unit is arranged at a position on the
outboard side of the outboard raceway surface in the stationary
member.
In other words, the sensor unit referred to above is preferably
arranged at a position on the outboard side of the outboard raceway
surface in the stationary member.
According to the analysis and the results of experiments, with
respect to both of the radially induced strain and the
circumferentially induced strain of the stationary member, only an
outboard portion of the stationary member is where the strain could
have a directionality in a positive sign or a negative sign in
dependence on the positive sign or negative sign of the load such
as, for example, the external force or the force, both referred to
previously. Accordingly, in order to detect the direction in the
positive or negative direction of the load, it is necessary for the
sensor unit to be mounted on the outboard position of the outer
member.
[13th Aspect]
The sensor equipped wheel support bearing assembly according to the
twelfth aspect, in which the sensor unit is mounted on a peripheral
surface of the stationary member.
In other words, the sensor unit is preferably fitted to the
peripheral surface of the stationary member. Although the sensor
unit may be fitted to any of the peripheral surface or end face of
the stationary member, deformation of the stationary member can
easily be transmitted to the mounting member, if the sensor unit is
fitted to the peripheral surface, and, therefore, the strain of the
stationary member can be detected with high sensitivity.
[14th Aspect]
The sensor equipped wheel support bearing assembly according to the
thirteenth aspect, in which the sensor unit is fitted to the inner
peripheral surface of the stationary member and the sealing unit
for sealing the annular bearing space between the outer member and
the inner member is provided on the outboard side of the sensor
unit.
In other words, where the sensor unit is fitted to the peripheral
surface on the side of the inner periphery of the stationary
member, the sealing unit for sealing the annular bearing space
between the outer member and the inner member is preferably
provided on the outboard side of the sensor unit.
If where the sensor unit is fitted to the peripheral surface on the
side of the inner periphery of the stationary member, the sealing
unit for sealing the annular bearing space is provided on the
outboard side of the sensor unit, the sensor unit will be immune
from any influence brought about by muddy water or the like and the
need to use the sealing unit dedicated for the sensor unit can be
dispensed with.
[15th Aspect]
The sensor equipped wheel support bearing assembly according to any
one of the fourth to seventh and eleventh to fourteenth aspects, in
which the mounting member does not undergo plastic deformation at
the maximum expected value of the external force acting on the
wheel support bearing assembly or the working force acting between
the wheel tire and the road surface.
In other words, the mounting member is preferably of a type that
does preferably not undergo plastic deformation at the maximum
expected value of the external force acting on the wheel support
bearing assembly or the working force acting between the wheel tire
and the road surface.
Once the plastic deformation occurs, the deformation of the
stationary member will not be accurately transmitted to the
mounting member enough to adversely affect the strain measurement.
However, if the mounting member does not undergo plastic
deformation at the maximum expected value of the external force
acting on the wheel support bearing assembly or the working force
acting between the wheel tire and the road surface, the deformation
will be accurately transmitted to the mounting member and the
strain of the mounting member can be detected with high
precision.
[16th Aspect]
The sensor equipped wheel support bearing assembly according to any
one of fourth to seventh and eleventh to fifteenth aspects, in
which the mounting member is made of a magnetostrictive material
such as, for example, Ni or the like having a negative
magnetostrictive constant.
In other words, although the mounting member may be made of any
material provided that it is a magnetostrictive material, it is
preferably a magnetostrictive material such as, for example, Ni or
the like having a negative magnetostrictive constant. If it is the
magnetostrictive material having the negative magnetostrictive
constant, the strain can be detected with high sensitivity.
[17th Aspect]
The sensor equipped wheel support bearing assembly according to the
first aspect, in which the sensor unit includes the sensor mounting
member and the displacement sensor.
[18th Aspect]
The sensor equipped wheel support bearing assembly according to any
one of the seventeenth, eighth and ninth aspects, in which the
sensor unit is in a plural number.
In other words, the sensor unit may be employed in a plural number.
If the sensor unit is in the plural number, the displacement at a
plurality of locations of the stationary member can be detected by
the plural displacement sensors and from respective outputs of the
plural displacement sensors, the load or the like acting on the
vehicle wheel can be detected and, therefore, the sensitivity of
detection of the load or the like on the vehicle wheel can be
increased.
[19th Aspect]
The sensor equipped wheel support bearing assembly according to any
one of seventeenth, eighth, ninth and eighteenth aspect, in which
the sensor unit is arranged on a portion on the outboard side of
the stationary member.
In other words, the sensor unit is preferably arranged on the
outboard portion of the stationary member.
According to the analysis and the results of experiments, with
respect to both of the radially induced strain and the
circumferentially induced strain of the stationary member, only a
portion on the outboard side of the stationary member is where the
strain could have a directionality in a positive sign or a negative
sign in dependence on the positive sign or negative sign of the
load such as, for example, the external force or the force, both
referred to previously. Accordingly, in order to detect the
direction in the positive or negative direction of the load, it is
necessary for the sensor unit to be mounted on the outboard portion
of the outer member.
[20th Aspect]
The sensor equipped wheel support bearing assembly according to the
nineteenth aspect, in which the sensor unit is provided on the
peripheral surface of the stationary member.
In other words, the sensor unit is preferably provided on the
peripheral surface of the stationary member. The sensor unit may be
provided on either the peripheral surface or the end face of the
stationary member, but if it is provided on the peripheral surface,
the deformation of the stationary member can easily be transmitted
to the sensor mounting member and the displacement of the
stationary member can be detected with high sensitivity.
[21st Aspect]
The sensor equipped wheel support bearing assembly according to any
one of the seventeenth, eighteenth, ninth and eighteenth to
twentieth aspects, in which the sensor mounting member of the
sensor unit will not undergo plastic deformation at the maximum
expected value of the external force acting on stationary member or
the working force acting between the wheel tire and the road
surface.
In other words, at the maximum expected value of the external force
acting on stationary member or the working force acting between the
wheel tire and the road surface, the sensor mounting member of the
sensor unit is preferably of a type that does not undergo the
plastic deformation.
Once the plastic deformation occurs, the deformation of the
stationary member will not be accurately transmitted to the sensor
mounting member enough to adversely affect the displacement
measurement, but if the sensor mounting member does not undergo
plastic deformation at the maximum expected value of the external
force or the working force, the deformation of the stationary
member will be accurately transmitted to the mounting member and
the displacement of the mounting member can be detected with high
precision.
[22nd Aspect]
The sensor equipped wheel support bearing assembly according to nay
one of the seventeenth, eighth, ninth and eighteenth to
twenty-first aspects, in which the displacement sensor is in the
form of an eddy current sensor, a magnetic sensor, an optical
sensor, a contact type sensor or an ultrasonic sensor.
In other words, for the displacement sensor, any of the eddy
current sensor, the magnetic sensor, the optical sensor, the
contact type sensor and the ultrasonic sensor can be employed.
* * * * *